Try googling for "AM transmitter circuit plans".

In amplitude modulation you take a CW (continuous wave) signal, of let us say, one megahertz. You then modulate the intensity with an audio signal, at say 1000 hertz.

So this 1 Mhz gets stronger and weaker at 1000 hertz.

The mixing of two frequencies like this gives rise to a more complex waveform called an AM signal.

http://www.google.ca/#hl=en&safe=off&q=%22amplitude+modulation%22+%2Btheory&meta=&aq=&oq=&fp=8a2e5f2ec75fca07

These appear like this, choose from these

http://images.google.ca/images?hl=en&safe=off&q=%22amplitude%20modulation%22%20%2Btheory&um=1&ie=UTF-8&sa=N&tab=wi

Each of those pages will give you pages and pages of informative hits.

In general if you have a 500 watt CW signal you can give it double sideband AM with 500 watts of extra power. Total power 1000 watts. 500 in the carrier and 250 in each sideband, upper and lower. if you try and go above 500 watts in the combined sidebands when the carrier is 500 watts you get what they call splatter...sort of the tail wagging the dog, or when the reference carrier is smaller than the signal.

You can also have single sideband suppressed carried, which eliminates the carrier and either the upper or lower sideband.

It is a complex beast.

http://images.google.ca/images?hl=en&safe=off&um=1&sa=1&q=%22single+sideband%22+%2Btheory&btnG=Search+images&aq=f&oq=&start=0

http://www.google.ca/search?hl=en&safe=off&um=1&q=%22single%20sideband%22%20%2Btheory&ie=UTF-8&sa=N&tab=iw&start=0

thanks for every body replied to my help demand this fast specially aurizon

but mr aurizon i know about the theory of the AM and the single side band

what i need is just a simple circuit that canmake the function of AM transmitter .a circuit i can make simulation to it at a simulation program before i carry it out on a printed circuit board

and that do not insult your effort done to help me

thanks

http://www.scribd.com/doc/21219701/Ramsey-AM-Radio-Transmitter-Kit-Instructions

http://www.google.ca/#hl=en&source=hp&q=%22am+transmitter%22+%2Bbasic+%2Blayout&btnG=Google+Search&meta=&aq=f&oq=%22am+transmitter%22+%2Bbasic+%2Blayout&fp=8a2e5f2ec75fca07

I understand your problem completely. I too have tried to use both Spice and Electronic Workbenceh to simulate an RF circuit. In my case a simple colpits oscilator. EWB and spice seem to go brain dead when presented with this. They refuse to let the circuit oscilate while the breadboarded circuit runs great. The only advice I have to offer is to keep playing with the circuit parameters you can eventually convince EWB that you intend for the circuit to oscillate but you have to provide much more loop gain than an actual circuit will require. (I tend to design oscilators from a feedback and controls standpoint since I am stronger there than in RF circuit techniques). EWB even has problems simulating an astable multivibrator. Maybe the designers purposely took pains to eliminate oscillations due to some programming problem dealing with making the program converge to a solution. I am sure there is some software GURU out there that can enlighten us. Until then, good luck.

Interesting that neither tool manages these cases well. What do EWB and Spice do when presented with an inverter whose output is tied to its input? Does it oscillate?